1. Field of the Invention
The invention relates to an oscillating motor having a cylinder with inward extending ribs, a motor shaft, outward extending vanes, a pair of cylinder covers surrounding the shaft and forming working chambers between the cylinder and the shaft, and a pressure equalization channel connecting ring shaped spaces having seals.
2. Description of the Related Art
A sealing arrangement of the type used in oscillating motors to seal off the motor shaft against the cylinder of the oscillating motor is known from DE 43 33 047 C1. The seal is intentionally supplied with a working pressure to achieve a dynamic preload. As a result, the advantage is obtained in an oscillating motor that, when there is no pressure in the hydraulic supply system, there is little friction between the motor shaft and the cylinder.
DE 100 62 477 C1 describes taking the pressure for preloading the seal from the working spaces. For this purpose, a groove leading to the ring-shaped space in which the seals are installed is stamped into the cover of the working chamber.
A general problem with pressure-preloaded seals arranged in pairs in an oscillating motor is that the pressure levels at the two seals are different, which means that a longitudinal force is created, which tries to shift the motor shaft with respect to the cylinder. This effect can be minimized, for example, by connecting the pressure-preloaded seals on the motor shaft at the front and rear ends of the working chambers to each other. A design of this type is known from, for example, DE 196 07 067 A1. It is disclosed that longitudinal bores are produced inside the cylinder and the motor shaft to connect the sealing spaces containing the seals to each other. The problem, however, is that a comparatively long bore must be produced.